(a) Field of the Invention
The present invention relates to an aperture stop for microscope condensers and, more particularly, to an aperture stop for microscope condensers having improved indications.
(b) Description of the Prior Art
On the accompanying drawings, FIG. 1 shows a side view of a microscope in general. In FIG. 1, numeral 1 designates an arm, numeral 2 designates a condenser, numeral 3 designates an aperture stop accommodated in the lower portion of the condenser 2, numeral 4 designates a revolver, and numeral 5 designates an objective mounted to the revolver 4. When the objective to be used for observation by the above-mentioned microscope is exchanged by revolving the revolver 4, it is necessary to change the aperture diameter of the aperture stop according to the numerical aperture of the objective to be used. For this purpose, an objective is provided with various indications on its outer surface as shown in FIG. 2, i.e., an indication 5a which represents the kind of objective (achromat, apochromat, etc.), an indication 5b which represents the magnification, and an indication 5c which represents the numerical aperture. Besides, a colour band 5d representing the magnification is provided so that the observer can easily know the magnification of the objective by means of the colour of the colour band. The aperture stop 3 of the condenser 2 is provided with an index mark and graduations representing numerical apertures. The observer knows the numerical aperture of the objective to be used for observation by looking at the numerical aperture indication 5c, which is provided on the outer surface of that objective, and operates the stop ring so that the index mark of the aperture stop 3 comes to the position of the numerical aperture graduation which is equal to the numerical aperture of the objective. As, however, the numerical aperture indication 5c of the objective 5 is very small, it is considerably difficult to see it. Besides, when the objective 5 is mounted to the revolver 4, its numerical aperture indication 5c sometimes comes to the side opposite to the observer's side (comes to the right side in FIG. 1). In such case, the observer cannot see the indications other than the colour band 5d and, therefore, cannot know the numerical aperture of the objective.